Fuinjutsu: Endless depths
by Kalle1111
Summary: A man wakes up after drinking on new years eve, only to find himself in Kabuto's body. Now he has to find a way to survive the world of Naruto while being on the "evil side" and without any plot armor.
1. Chapter 1

**I'm new to writing and subsequently quite inexperienced, as such any and all constructive criticism is welcome.**

 **Disclaimer: I do not own Naruto**

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Ch. 1

He woke up with a splitting headache. There were only so many occasions he would drink, however last night was new years eve and he foolishly thought a few glasses won't hurt.

Something felt off, the normally quite fresh, air felt stale and strangely humid, but without his glasses and with such a headache he had other pressing matters.

Slowly he felt for his glasses on the small nightstand next to the bed. _'Finally'_.

As he put his glasses on he was startled as he noticed these were not _his_ glasses.

Using one hand to massage his head to try and reduce his ever growing headache, he slowly looked around.

He was in a dimly lit room without any windows, apart from the bed and the nightstand there was only a table, which had a lamp on top of it and a chair with neatly folded clothes.

For a moment he thought he had been abducted but then he reminded himself, that if that were the case, he would be bound and probably gagged too. He shivered thinking of what could possible happen in such a case.

 _'I really shouldn't watch so many horror movies'_

He stood up and started making the bed out of habit.

 _'Still even if I haven't been abducted, I should try not to make too much noise, see if I can get a read on this strange situation'_

As he was thinking he saw something flash in has peripherals and was abruptly startled by a metallic clang.

He spun around and readied himself until his vision landed on a curiously formed piece of metal which was lying innocently on the ground next to him.

His brain short circuited. _'This_ _has_ _to be a prank'_

He bent down to pick up the kunai. It was made of surprisingly light but still solid metal.

As strange as the situation already was, he subconsciously corrected his grip on the knife.

 _'OK this is getting past the prank stage by quite a bit. And even a prank wouldn't explain this shitty headache, maybe I was waking up and they actually hit me over the head?'_

He immediately searched for an injury but was surprised to find nothing but smooth skin and hair.

 _'Was my hair always this long?'_ he wondered.

Just as he was about to to look for a mirror, the door suddenly opened and a strangely clothed teenage boy stepped in and knelt on one knee.

"The mission was successful. Here is the item you requested." he then handed him a scroll and left.

 _'This day is getting weirder and weirder. Did that guy just move at superhuman speed? And more importantly how the hell was I able to keep track of him!'_

He decided to open that particular can of worms later and resumed trying to find a mirror.

After 5 more minutes of uselessly going over the same spots over and over again, he remembered he still had the knife.

Carefully handling it, as not to cut himself, he looked at his reflection.

 _'…'_

Looking back at him, was not the usual face with the faded freckles around the nose and the slight stubble at the chin, that he never managed to get quite ride of.

There were no freckles, neither was there any stubble.

His eyes widened "What the …" before he could finish the sentence, or begin to notice that even his voice changed, he fell unconscious.

~Line Break~

When he woke up again, the headache was gone.

 _ **'Merging of memories'**_ A voice in his head suddenly supplied.

 _'Great, first I wake up in this strange room and then I am hearing voices in my head. At least I can blame insanity for this lovely situation'_

But when he started concentrating, he suddenly remembered things he did never experience, like learning how to throw the knife, which was still in his hand.

Moreover he remembered when he was given his name, Kabuto. However that was also the thing that troubled him, because while Kabuto was not _his_ name, he subconsciously recognized it as such and any attempts to remember _his_ name ended on that particular scene.

He realized how oblivious he had been.

 _'Or perhaps just in denial'_

The strange setting, the glasses, the knife and lastly the boy. Either he was in a medieval Japan where super-humans existed or he was in the anime Naruto. Or maybe he was just _simply insane_.

 _'Given I don't really like the sound of number three and considering my name I'll bet on the second'_

He was not completely sure what to feel. On one hand he had just, in a second, lost his whole former life, but on the other hand was in the world of Naruto and had gained memories of chakra, jutsu and other cool stuff. He practically felt the chakra flowing through his body.

 _'Meh my former life wasn't much anyway, alone, relatively low wage and a shitty boss.'_

Then he suddenly realized something _'Ugh, Orochimaru isn't really a good boss either, and he is kind of pedo, but at least he leaves me_ _some_ _leisure.'_

 _ **'And he is your best way to attain power'**_ the strange voice added again.

 _'Hello..?'_ He was getting creeped out, but no answer came.

 _'Wait, the last times the voice only came to offer explanations/corrections. So if I just ask myself what this voice is?'_

 _ **'A residue of the memory merging. It gives you knowledge you, in theory, already know, but can't access yet. It will probably disappear during the week.'**_

 _'OK this feels strange'_

Leafing through the new memories for a few more minutes, he decided to explore the surrounding area and refresh some of his memory.

 _'If I'm working under Orochimaru I can't allow any slip-ups. I wouldn't like to be the one lying on the operation table this time.'_

Stepping outside the door there was a long hallway with 2 directions. Looking in both direction, he decided to head to the training ground.

 _ **'Left side'**_ the voice supplied.

After an uneventful walk through dimly lit corridors, he came to face with a large door. Mustering up his courage and desperately hoping this to actually be the training ground and not something else, he stepped in.

The hall was empty, save for a few wooden training dummies propped up against the far wall.

He suddenly wondered how these dummies had any chance of surviving the weapons and sometimes even jutsu they faced.

Shrugging it off, he tried molding chakra. _'Successful on the first try! I guess Kabuto really had perfect chakra control'_

Sitting down he pondered on how to get strong quickly.

 _'The world of Naruto is by no means as forgiving as my former. If I want to survive, especially on the evil side, without plot armor, I need a way to guaranty my survival'_

He started meditating to get more details of this world. _'The Anime was always annoyingly vague'_

After about 30 minutes he suddenly opened his eyes and grinned a smile a bit too wide.

 _' Fuinjutsu!'_

There were so many gaps in the system to be exploited that it wasn't even funny anymore.

With new determination, he stood up and started to walk towards the library.


	2. Chapter 2

**To avoid confusion, when talking about the "old" _Kabuto,_ he is written like this.**

 **Disclaimer: I do not own Naruto.**

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Ch. 2

Using his spare time while walking, he continued pondering on his current situation.

Since the anime was quite vague about Orochimaru's and _**Kabuto's**_ , _'his'_ , he reminded himself, doings up to canon, he was not yet sure where he had landed, time wise. The only pointers where, that he could not remember interacting with Sasuke or participation in any chunin exam.

And since he was still in one of Orochimaru's secret hideouts and had yet to start making his fake backstory for Konoha, he was sure to still have some more time before the exams.

Quietly humming he entered the library. It was just as deserted as the training grounds.

 _'I wonder why everything is so empty...'_

 _ **'It is during the night.'**_

 _'Cool, now I have my own internal clock'_

Satisfied to know the emptiness was not just some random ploy from Orochimaru, he went in search for the fuinjutsu section.

Orochimaru had amassed quite a few books in his quest to learn all jutsu.

 _'Such a ridiculous and childish dream.'_

He didn't see the point in learning all the jutsu, there was just no way to actually be able to remember all of them, even the op hack, named sharingan, wasn't able to store an unlimited amount of information and still be able to instantly access it.

 _'There'_ he thought, pulling out a scroll about advanced fuinjutsu.

Luckily _**Kabuto**_ had already started learning the art of seals and had advanced quite far, however to be on the safe side, he decided to re-read at least the more complicated concepts.

Even though Orochimaru strangely had only little interest in seals and dropped the entire topic, after his partly failure at the cursed seal, he still had all of his scrolls.

~Line Break~

Kabuto was exhausted, there is only so much reading he can do per day, until his brain feels like mush.

He had quite a few ideas on how to use seals to imitate modern, or even fictional, technology.

Seals, in it's purest form, had an unlimited versatility. However, they worked similar to a computer, if one part of it is not up to par, it does not work the way intended.

 _'I should probably try and see where I can get advantages out of my future knowledge'_

Taking some sealing utensils with him, he began the way back to his room.

 _'Speaking of future knowledge, what should I change and what can I even change?'_

There where three possible ways he would have to change future happenings.

The first where if it would benefit him, the second if he could not morally allow himself to be idle and the last and by far most unpleasant, if he was forced to do so.

With each such decision, his accuracy at predicting the future would be reduced.

 _'Maybe I should stay low and only affect relatively unimportant actors. There were quite a few side arc kekkei genkai.'_

Being in a good mood, due to the newfound revelation that he could liberate **cough** _steal_ **cough** some kekkei genkai without diverging the plot too much, he started humming again, to make the walk more enjoyable.

~Line Break~

 _Bob PoV_

Bob was your average Otogakure ninja. He was from Kumo, however had been kicked out of the ninja academy after failing graduation for the third time. When he had been at his low, his savior Orochimaru-sama had come to his rescue, and granted him power.

Bob had been delighted to finally be useful.

However, now, Bob had a serious problem. He had completed a mission and was supposed to deliver the recovered cargo to Orochimaru-sama's second in command, Kabuto.

But when Bob had tried approaching him, he had been smiling a tad too wide and even started humming. **Kabuto-sama** **was humming**!

As brave as Bob was, even he was not dumb enough to approach a humming Kabuto.

The last one who did that was so unrecognizable Orochimaru-sama had been unable to experiment on him.

So Bob had waited a little, in front of Kabuto-sama's room. He did not want to follow and see which poor fellow suffered his wrath.

But when Kabuto had come back, he was still humming!

Deciding to cut his losses and risk punishment, Bob threw the cargo on Kabuto's bed and quickly removed himself of the vicinity.

~Line Break~

 _Kabuto PoV_

When he came back to his room, another package had been delivered.

'I wonder what _**Kabuto**_ had all those ninja collecting'

Not two seconds later, he received his answer.

 **'They were tasked to bring DNA-Samples of people with kekkei genkai.'**

'Well that is convenient, now I can use these to work on the theory and practical progress'

Carefully unpacking both packages, he found multiple vials with blood in them. They were all labeled and had an assortment of names.

'This looks quite promising'

For now, Kabuto decided to seal all of them in a newly made storage-scroll.

 _'Until I've worked some more on my fuinjutsu, I shouldn't waste these precious samples. **MY precious** samples.'_

He smirked.

 _'Tomorrow will be eventful.'_

Deciding to catch at least a little bit of sleep, Kabuto went to bed.


End file.
